oh i can assure you, you will gain mass very well on bread alone as it breaks down to glucose in the body. also, a carb is a carb and when it comes down to building muscle it's mostly about meeting metabolic requirements, necessary blood nitrogen levels as well as enough calories (which any type of carbs will fulfill), to create an anabolic rather than catabolic environment
A calorie is not a calorie and a macroinutrient is not just a macronutrient as far as building a good physique goes.
Bread is a simple carb loaded with preservatives and nowhere near as good as slower digesting carbs such as brown rice,yams,oats,etc.
For a quick digesting carb,try dextrose or honey post-workout.
Bread tastes great,but it sux as far as nutrition goes and as a carb source for bodybuilding it flat out blows!!